JPH0315544A - Laminated polyester film - Google Patents

Abstract

PURPOSE:To enhance transparency and easy slidability and to prevent the generation of a Newton ring by using particles of a specific org. polymer as particles added to a coating layer. CONSTITUTION:A coating layer based on org. polymer particles having a refractive index of 1.2 - 1.8 and a water-soluble or water-dispersible resin is provided to at least the single surface of a polyester film and the ratio (D/d) of the mean particle size D of the org. polymer particles and the thickness (d) of a coating layer is set to a range of 1.1 - 8.0 and the mean particle size D of the org. polymer particles is set to 0.8mum or more and the addition amount thereof is set to 0.1 - 20wt.%. Further, the center line mean roughness of the outer surface of the coating layer is set to 0.2mum. As the org. polymer particles, particles of a divinyl benzene/styrene copolymer (crosslinked), polyimide and a silicone resin are designated. The water-soluble or water-dispersible resin may be dissolved or dispersed in water and a urethane resin, a polyester resin, polyvinyl alcohol, a vinyl resin, a copolymer thereof and an acrylic resin can be designated.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a laminated polyester film.

More specifically, we will refer to laminated polyester films with excellent transparency and slipperiness, especially films that do not produce Newton rings when the films are stacked together (hereinafter such films are referred to as "Anti-Newton films").
Newton ringf 1 1m) J, abbreviated as FAN film. ), and relates to a laminated polyester film suitable as a polyester film.

[Conventional technology]

Polyester biaxially stretched film has excellent properties such as mechanical properties, electrical properties, dimensional stability, and transparency, so it is used as a magnetic recording material, packaging material, electrical insulation material,
It is widely used as a base film for many applications such as graphic arts materials and photographic materials. Highly transparent polyester film has a smooth film surface, so it has very poor sliding properties between films, which can cause surface defects such as blocking and scratches, deterioration of winding performance and appearance, and even problems during processing. It is known that this causes poor workability, or that Newton rings occur when such films are overlapped. Moreover,
These drawbacks become more noticeable as the base film becomes more transparent. In this way, in polyester films, transparency tends to conflict with anti-newton properties and smoothness, and it is difficult to satisfy both properties at the same time.Furthermore, it is difficult to satisfy both properties at the same time. It was difficult to obtain. In order to obtain films with excellent properties, various studies have been made as follows.

(1) A polyester film in which an organic polymer binder containing inorganic particles and silica sol is coated on the transparent film surface (JP-A-61-2528, JP-A-60-6)
1259).

(2) A polyester film in which minute longitudinal protrusions are formed by stretching and breaking a resin layer coated on the transparent film surface (Japanese Patent Application Laid-open No. 61-204240).

[Problem to be solved by the invention]

However, the above-mentioned polyester film has the following problems.

In the film of (1) above, when inorganic particles are used, it is difficult to maintain abrasion resistance while imparting transparency and slipperiness, particularly anti-Newtonian properties.

On the other hand, like the film of (1), the film of (2) above also has minute protrusions, so it was difficult to impart slipperiness, especially anti-newton property, without impairing transparency.

The present invention aims to eliminate these drawbacks of the prior art and provide a polyester film that is excellent in transparency, slipperiness, and anti-newton properties.

[Means to solve the problem]

The present invention comprises: (1) A laminate comprising a polyester film on at least one side of which is provided with a coating layer mainly composed of organic polymer particles having a refractive index of 1.2 to 1.8 and a water-soluble or water-dispersible resin. The polyester film has a ratio (D/d) of the average particle diameter D of the organic polymer particles to the thickness d of the coating layer of 1.
1-8. (2) The average particle diameter D of the organic polymer particles is 0.8 μm or more and the addition rate is 0.1 to 20% by weight. The laminated polyester film according to claim 1, (3) the outer surface of the coating layer has a center line average roughness of 0. 2μm
(4) An overlay film for a scanner comprising the laminated polyester film according to claim 3, which is characterized by the above.

In the present invention, polyester refers to well-known polyesters, specifically, for example, terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, bis-α,β(2chlorophenoxy)ethane-4,4'-dicarboxylic acid, adipic acid, and sebacin. Examples include polyesters obtained by polymerizing at least one difunctional carboxylic acid such as an acid and at least one glycol such as ethylene glycol, triethylene glycol, tetramethylene glycol, hexamethylene glycol, and decamethylene glycol. I can do it. In addition, the polyester may be blended or copolymerized with other types of polymers within a range that does not impede the purpose of the present invention.
Antioxidants, heat stabilizers, lubricants, pigments, ultraviolet absorbers, etc. may be included.

The intrinsic viscosity of the polyester (measured in orthochlorophenol at 25°C) is preferably 0. 4 to 2.0,
More preferably, those in the range of 0.5 to 1.0 are usually used. In the present invention, particularly excellent effects can be obtained when polyethylene terephthalate or polyethylene-2,6-naphthalate is used as the polyester.

The coating layer referred to in the present invention must be provided on at least one side of the polyester film. And, the coating layer is
Refractive index is 1.2 to 1.8, preferably 1.35 to 1.6
It is necessary that the main components are organic polymer particles and a water-soluble or water-dispersible resin.

When the refractive index of the organic polymer particles is not within this range, that is, 1.
Even if it is smaller than 2 or larger than 1.8, the difference in refractive index will cause image distortion, which is especially noticeable when viewed through magnified transmission, and will affect the transparency of the film. This is not desirable because it does not make full use of the resources.

Further, it is necessary that the ratio (D/d) between the average particle diameter D of the organic polymer particles and the thickness d of the coating layer is in the range of 1.1 to 80. This is not preferable because if D/d is less than 1.1, the lubricity is insufficient.

On the other hand, if D/d is greater than 80, the added particles will easily fall off and will fall off during handling, turning into powder and causing film defects, which is not preferred.

In addition, the average particle diameter D here is the weight average of the diameters of particles measured using a centrifugal sedimentation type particle size distribution analyzer (SACP.2 type, manufactured by Shimadzu Corporation).

Further, the particles used in the present invention need to be organic polymers. This is because when using conventional inorganic fine particles, their affinity with resins is insufficient compared to organic polymers, especially acrylic and styrene polymers, which are preferred. This is not desirable because it will fall off and become a defect. Further, when the average particle diameter of the particles used is 0.8 μm or more, the defects caused by the scraped particles are more noticeable, so the improvement effect by using the organic polymer particles is more noticeable, which is preferable.

The organic polymer particles used in the present invention have a refractive index of 1.2 to
The type of polymer is not particularly limited as long as it is a polymer particle within the range of 1.8. The molecular weight of the organic polymer is not particularly limited, but is usually 5,000 or more, preferably 10,000 or more. Furthermore, the surface activity or inactivity of the organic polymer particles is not particularly limited. Examples of such organic polymer particles include divinylbenzene/styrene copolymer (crosslinked)
Examples include polyimide, silicone resin particles, etc. However, when adjusting the particle size to a predetermined size, it is more preferable to use particles made to a predetermined size by particle manufacturing conditions such as emulsion polymerization rather than by a method such as pulverization, in view of quality variations.

Further, it is preferable that the organic polymer particles in the present invention have a temperature at 10% weight loss in a heating loss curve of 350°C, preferably 370°C, and more preferably 400°C or higher. The upper limit of the temperature at the time of 10% weight loss is not particularly limited, but usually about 6000C is the manufacturing limit.

In addition, the sphericity (major axis/
(breadth axis) is preferably 1.2 or less, more preferably 1.1
The following cases are suitable because the quality is stable.

The average particle diameter D of the organic polymer particles to be used has only to have a ratio (D/d) to the thickness d of the coating layer in the range of 1.1 to 80, and its absolute value is not particularly limited. Usually 0
．． The thickness is 3 μm or more, preferably 0.8 μm or more, and more preferably 2 μm or more.

The amount of organic polymer particles added in the present invention is preferably 0.1 to 20% by weight of the entire coating layer from the viewpoint of slipperiness and abrasion properties.

In the present invention, the water-dispersible or water-soluble resin may be dissolved or dispersed in water, and its type is not particularly limited, but typical examples include urethane resin, polyester resin, polyvinyl alcohol, and vinyl chloride. Representative examples include vinyl resins such as vinyl acetate, copolymers thereof, acrylic resins, and mixtures of these various resins. Furthermore, various additives such as antistatic agents, surfactants, antifoaming agents, etc. may be appropriately added as necessary within a range that does not deteriorate the properties.

However, among these, water-dispersible acrylic resins, especially those containing alkyl acrylate or alkyl methacrylate as a main component, are preferable, with 30 to 99.9 mol% of this component and vinyl monomers copolymerizable with these and having a functional group. Water-dispersible resins containing 70 to 0.1 mol% of polymeric components are more preferred than water-soluble resins.

A vinyl monomer that can be copolymerized with alkyl acrylate or alkyl methacrylate and has a functional group imparts hydrophilicity to the resin and improves the water dispersibility of the resin.
Alternatively, it is preferable to have a functional group that improves the adhesion between the resin and the polyester film or other coating layer provided on the undercoat layer. Preferred functional groups include a carboxyl group or a salt thereof, an acid anhydride group, and a sulfone group. acid group or its salt, amide group or alkylolated amide group,
These include amino groups (including substituted amino groups), alkylolated amino groups, salts thereof, hydroxyl groups, and epoxy groups. Particularly preferred are carboxyl groups or salts thereof, acid anhydride groups, and epoxy groups. Two or more types of these groups may be contained in the resin.

The reason why the content of alkyl acrylate or alkyl methacrylate in the acrylic resin is preferably 30 mol % or more is because coating formability, coating film strength, and blocking resistance are improved. Alkyl acrylate or alkyl methacrylate in acrylic resin is 99.9
The reason why the amount is preferably mol% or less is that by introducing a compound having a specific functional group as a copolymerization component into the acrylic resin, it becomes easier to water-solubilize and water-disperse the resin, and
This is to stabilize the state over a long period of time, and also to improve the adhesion between the coating layer and the polyester film layer.
This is because it is possible to improve the strength, water resistance, and chemical resistance of the coating layer due to the reaction within the coating layer, and also to improve the adhesion between the film of the present invention and other materials.

Examples of alkyl groups in alkyl acrylates and alkyl methacrylates include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, lauryl group,
Examples include stearyl group and cyclohexyl group.

As the vinyl monomer having a functional group copolymerizable with alkyl acrylate or alkyl methacrylate, the following compounds having functional groups such as a reactive functional group, a self-crosslinking functional group, and a hydrophilic 1l 12 group can be used.

Examples of compounds having a carboxyl group or a salt thereof, or an acid anhydride group include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, metal salts of these carboxylic acids with sodium etc., ammonium salts, Alternatively, maleic anhydride may be mentioned.

Examples of compounds having a sulfonic acid group or a salt thereof include vinyl sulfonic acid, styrene sulfonic acid, metal salts of these sulfonic acids with sodium, ammonium salts, and the like.

Examples of compounds having an amide group or an alkylolated amide group include acrylamide, methacrylamide, N-methylmethacrylamide, methylolated acrylamide, methylolated methacrylamide, ureido vinyl ether, β-ureido isoptyl vinyl ether,
Examples include ureidoethyl acrylate.

Examples of compounds having an amino group or an alkylolated amino group or a salt thereof include diethylaminoethyl vinyl ether, 3-aminopropyl vinyl ether, 2-aminoptyl vinyl ether, dimethylaminoethyl methacrylate, dimethylaminoethyl vinyl ether, and amines thereof. Examples include those in which the group is methylolated, and those in which the group is converted into a quaternary chloride using an alkyl halide, dimethyl sulfate, sultone, or the like.

Examples of compounds having a hydroxyl group include β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate,
β-hydroxypropyl acrylate, β-hydroxypropyl methacrylate, β-hydroxy vinyl ether, 5-hydroxypentyl vinyl ether, 6-hydroxyhexyl vinyl ether, polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate, polypropylene glycol monoacrylate, polypropylene glycol monomethacrylate Examples include.

Examples of the compound having an epoxy group include glycidyl acrylate and glycidyl methacrylate.

Furthermore, in addition to the above compounds, the following compounds may be used in combination. Namely, acrylonitrile, methacrylonitrile, styrenes, butyl vinyl ether, mono- or dialkyl maleic acid esters, mono- or dialkyl fumaric acid esters, mono- or dialkyl itaconic acid esters, methyl vinyl ketone, vinyl chloride, vinylidene chloride, vinyl acetate, vinyl pyridine. , vinylpyrrolidone, vinyltrimethoxysilane, etc., but are not limited to these.

The acrylic resin may contain a surfactant, but the low molecular weight surfactant contained in the acrylic resin may be concentrated during the film-growing process, accumulate at the interface between particles, or be difficult to coat. It may migrate to the interface between layers, causing problems with the mechanical strength, water resistance, and adhesion of the coating layer to the laminate. In such a case, a polymer obtained by so-called soap-free polymerization that does not contain a surfactant can be used.

However, among these, there is a water-dispersible acrylic resin in which the main polymer is a copolymer of methyl methacrylate and ethyl acrylate at a molar ratio of 35/65 to 65/30, and 1 to 5% by weight of each of -COOH and CH20H are introduced. , is particularly suitable in terms of easy adhesion and transparency of the laminated film.

In addition, in order to improve the adhesion, water resistance, solvent resistance, and mechanical strength of the coating layer, methylolated or alkylolated urea-based melamine-based, acrylamide-based, polyamide-based, etc. are used as crosslinking agents. It may also contain reactive compounds such as resins, epoxy compounds, aziridine compounds, blocked polyisocyanates, and vinyl compounds.

Furthermore, if necessary, antifoaming agents, coating properties improvers, thickeners,
It may also contain antistatic agents, antioxidants, ultraviolet absorbers, dyes, pigments, and the like.

The polyester film constituting the film of the present invention is at least biaxially stretched by a conventional method, and has a thickness of preferably 2 to 500 μm, preferably 50 to 250 μm.
The range of 15 to 16 is more preferable because it is excellent in practical handling as a base material. Furthermore, the haze (turbidity) of polyester film is 10
It is preferably 4.0% or less per 0 μm, more preferably 3.0% or less per 0 μm.
．． It is 0% or less, more preferably 1.5% or less.

The laminated thickness of the coating layer constituting the film of the present invention is 0.00
The thickness is preferably 5 to 10 μm, more preferably 0.5 to 4 μm. If the lamination thickness is less than 0.005 μm, uniform lamination is difficult and particles easily fall off, which is not preferable. If the laminated thickness exceeds 10 μm, it is not preferable because manufacturing suitability such as drying property and coating suitability deteriorates.

Next, a typical manufacturing method of the present invention will be described using a polyethylene terephthalate (hereinafter also referred to as "PET") film, but the method is not limited thereto.

First, PET chips polymerized by a conventional method are
It is melt-extruded through a slit die at 310°C and cooled on a cooling drum at 20 to 80°C while applying an electrostatic charge to produce an unstretched film.

At this time, the intrinsic viscosity of the unstretched film is 0. It is desirable that it is 5 or more. Next, the unstretched film or the unstretched film is heated to 70 to 120°C.
An aqueous solution prepared by adjusting a predetermined amount of a mixed composition of organic polymer particles and water-soluble or water-dispersible resin in advance is applied onto the film stretched 2.0 to 7.0 times, and the coating film is dried. After providing a predetermined coating layer, it is stretched at 70 to 150°C. When coating on an unstretched film, the thickness in the longitudinal direction is 2.0 to 7.
0 times and 2.0 to 7.0 times in the transverse direction simultaneously, or 2.0 to 7.0 times in the case of using a uniaxially stretched film. In addition, the biaxially oriented film was further added to 100 to 1
It may be stretched 1.1 to 3.5 times in at least one direction at 80°C. Furthermore, the biaxially oriented film can be
The treatment may be performed for 1 to 60 seconds while providing 0 to 10% relaxation at 0 to 240°C.

The coating method is not particularly limited, and extrusion lamination and melt coating methods may be used, but water-soluble or water-dispersed coating materials are gravure coated because it is possible to coat a thin film at high speed. It is preferable to apply a known method such as a coating method, a reverse coating method, a spray coating method, a kiss coating method, a die coating method, or a metal ring bar coating method. At this time, the film may be subjected to known surface treatments such as corona discharge treatment in air or in various other atmospheres, if necessary. In addition, the coating material concentration,
The coating film drying conditions are not particularly limited, but it is desirable that the coating film drying conditions be within a range that does not adversely affect the properties of the laminated polyester film.

The film of the present invention is suitable for use as an overlay for a scanner, especially when it is enlarged to a high magnification. The characteristic values in the present invention are based on the following measurement methods and evaluation criteria.

(1) Transparency The haze was measured based on JIS K6714 using a SEP-H-2 type turbidity meter (manufactured by Nippon Seimitsu Kogaku Co., Ltd.).

(2) Friction coefficient Measured based on ASTM-01894.

(3) Place the film to be measured on a flat plate with the coating layer on top (if it is a double-sided coating layer, perform the measurement on each layer), place it on a flat plate, and place it on a flat plate.
0) on top and press lightly with a cloth. At that time, those in which Newton's rings were generated were marked as "x", and those in which Newton's rings were not produced were marked as rOJ.

(4) Sharpening feather razor blade S (single edge, carbon steel blade thickness 0.245m)
m) Apply 500 g to one blade, press it perpendicularly to the coating layer cut into a 1/2 inch width, push it further 0.5 mm, and run it for 20 cm (running tension: 500 g)
, traveling speed 6. 7 cm/sec).

At this time, the amount of scraping attached to one edge will be compared with the coating layer of Comparative Example 7. When the amount of scraping was 150% or less of Comparative Example 7, it was determined as "○", and when it was more than that, it was determined as "x".

(5) Ratio of average particle diameter D to coating layer thickness d (D/d) 19 20 From the average particle diameter D determined by the sedimentation method and the coating layer thickness d determined from the cross section using an optical microscope, the ratio (D/d) d) was calculated.

(6) Easy slippage In accordance with JIS-B-0601, a stylus-type surface roughness meter SD-3 manufactured by Kosaka Laboratory Co., Ltd. was used to measure the cutoff of 0.
．． The average roughness Ra (μm) was measured at a measurement length of 25 mm and a measurement length of 1 mm.

(7) Scanner characteristics When used as an overlay for a scanner, those that do not have transparency, Newton rings (rainbow pattern), or screen blurring when enlarged (not a practical problem) are marked as "○", others are marked as "x". I judged it.

(8) Refractive index of organic polymer particles The refractive index is determined from the Betzke line using the immersion method.

〔Example〕

Next, the present invention will be explained in more detail using Examples and Comparative Examples, but the present invention is not limited to the following Examples.

Example 1 A PET homopolymer chip (
It was dried under reduced pressure (3 mmHg) at 180° C. for 2 hours. This chip is 280
The film was fed to an extruder at 90°C, melted and extruded from a T-type nozzle, and wound around a cooling drum with a surface temperature of 20°C using an electrostatic application method to cool and solidify to form an unstretched film. The film was stretched 3.3 times in the machine direction by roll stretching.

Next, divinylbenzene/styrene copolymer particles with an average particle size of 1.5 μm manufactured by Japan Synthetic Rubber Co., Ltd., and methyl methacrylate and methyl acrylate copolymer (but -C
After applying a water-dispersed coating material in which 2 mol % of H2 0H and -COOH (introduced to make it hydrophilic) were mixed at a solid content weight ratio of 2:98 on one side of the uniaxially stretched film using a metal ring, The coated layer was stretched 3.6 times in the transverse direction at 100° C. while drying, and stretched to 210° C. while relaxing by 2% in the transverse direction.
℃ for 5 seconds to form a coating layer of 0. A laminated film having a thickness of 100 μm in which 3 μm layers were laminated was obtained.

The coating layer thus obtained had a ratio of average particle diameter to coating layer thickness (D/d) of 5.

Further, the properties of the laminated film were as shown in Table 1, and it was excellent in both transparency and slipperiness, and was also excellent in abrasion resistance of the coating layer, anti-newton property, and scanner properties.

Comparative Example 1 The same procedure as in Example 1 was carried out except that synthetic calcium carbonate was used as the particles.

Comparative Example 2 Example 1 except that alumina was used as the particles used
It was carried out in the same way.

Comparative Example 3 Example 1 except that silica was used as the particles used.
It was carried out in the same way.

Comparative Example 4 The same procedure as in Example 1 was carried out except that titanium oxide was used as the particles.

Comparative Example 5 The same procedure as in Example 1 was carried out except that the thickness of the coating layer was 2.0 μm.

23 Example 2 The same procedure as Example 1 was carried out except that the thickness of the coating layer was 1.0 μm.

Example 3 The same procedure as Example 1 was carried out except that the thickness of the coating layer was 0.1 μm.

Comparative Example 6 The same procedure as in Example 1 was carried out except that the thickness of the coating layer was 0.01 μm.

Example 4 The same procedure as in Example 1 was carried out except that the average particle diameter of the particles used was 0.4 μm and the thickness of the coating layer was 0.2 μm.

Example 5 The average particle size of the particles used was 1. 0μm, and the thickness of the coating layer is 0. The same procedure as in Example 1 was carried out except that the thickness was 5 μm.

Example 6 The average particle size of the particles used was 5. The same procedure as Example 124 was carried out except that the thickness of the coating layer was 0 μm and the thickness of the coating layer was 2.5 μm.

Comparative Example 7 The same procedure as in Example 1 was carried out except that no particles were added.

26 [Effects of the Invention] Since the laminated polyester film of the present invention uses specific organic polymer particles as particles added to the coating layer, it has excellent transparency and slipperiness, and at the same time, particles in the applied coating layer. It has the characteristics that it does not easily fall off and does not generate Newton rings.

Claims (4)

[Claims] (1) A laminated polyester film comprising a coating layer mainly composed of organic polymer particles having a refractive index of 1.2 to 1.8 and a water-soluble or water-dispersible resin on at least one side of the polyester film. Then, the ratio (D/d) of the average diameter D of the organic polymer particles to the thickness d of the coating layer is 1.
A laminated polyester film characterized in that the polyester film has a molecular weight in the range of 1 to 8.0. (2) The laminated polyester film according to claim 1, wherein the average particle diameter D of the organic polymer particles is 0.8 μm or more and the addition rate is 0.1 to 20% by weight. (3) The laminated polyester film according to claim 1, wherein the center line average roughness of the outer surface of the coating layer is 0.2 μm or more. (4) An overlay film for scanners comprising the laminated polyester film according to claim 3.